IV Start Device and Method

ABSTRACT

A method for starting an intravenous fluid line (IV) is disclosed where a combination of a syringe body with hypodermic needle, a dual ampoule with separate reservoirs for bicarbonate and an anaesthetic, a trocar and a cannula are configured so that the steps of injecting a wheal of a buffered anaesthetic, retracting the needle tip, lancing a vein with the trocar, and withdrawing the trocar tip so that the cannula remains in place in the vein may be accomplished in a single coordinated action by one skilled in the method, such as with one hand while the other hand performs manipulations on the vein and IV site.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/277,311 filed 2010 Dec. 25, which claims the benefit of 35 U.S.C.§119(e) for priority to U.S. Provisional Patent Application No.61/291,869 filed Jan. 1, 2010; said priority documents beingincorporated herein in entirety by reference for all that is disclosedtherein.

FIELD OF THE INVENTION

This invention relates generally to methods for reducing pain andmanipulation when starting medical infusion lines with intravenouscannulas.

BACKGROUND

Intravenous infusion of medication has proved highly effective intreatment of a wide range of clinical conditions, as well as in managinggeneral anaesthesia. Intravenous medications are commonly introducedthrough an indwelling cannula, most commonly into a peripheral vein,either in combination with a pharmacological acceptable diluent or inalternation therewith. However, the procedure for establishing anintravenous infusion line, more commonly termed an “IV”, can be painful,and is sometimes unsuccessful.

Pain continues to be an important factor in the successful placement ofthe IV. Not uncommonly, patient discomfort can lead to prematurewithdrawal of the trocar without first establishing patency of venousplacement. Thus there is an unmet need to reduce pain associated withstarting an IV.

In order to reduce pain when starting an IV, it has been found thatsubcutaneous administration of a local anaesthetic in advance of theprocedure frequently provides relief. A wheal of lidocaine(2-diethylamino-N-[1,6-dimethylphenyl]acetamide), typically administeredas a hydrochloride salt, induces field blockage of pain immediately uponadministration. Related local anaesthetics, such as described inGoodman's Pharmacological Basis of Therapeutics, may also be used. It isdesirable to administer the minimum amount of these substances as neededto achieve the desired effect.

The local anaesthetic can be administered with a very fine needle, suchas a 30 gauge needle, in order to further minimize pain. Needles of thissize are typically too small, however, for intravenous therapy. So aseparate trocar, more commonly 25 to 16 gauge in size, is used to startthe IV. Thus the typical procedure requires two separate devices, thefirst to administer the local anaesthetic and the second to start theIV, leading to delay and complexity, requiring additional supplies andprocedures, and is cumbersome.

Formulation of buffered mixtures is further complicated because the mostcommonly used local anesthetics are unstable when mixed with a buffersuch as sodium bicarbonate, unless used promptly. It is known that delayin usage may lead to weakening of the drug, presumably due todecomposition at neutral or near neutral pH.

Ampoules with breakable necks are also known, and may be used to load alidocaine:buffer mixture at the point of use. However, breakableampoules are not uncommonly associated with hand injuries due to sharpedges, and the use of two ampoules to prepare a solution at the bedsideis complicated and risks contamination. A frangible seal separating twosolutions is described in U.S. Pat. No. 5,261,903 to Dhaliwal, whichrelates to preparation of buffered anaesthetic solutions for localinjection. A displaceable bung is also described in U.S. Pat. No.3,464,414 to Sponnoble. However, these containers pose unrealistic costand complexity in modern clinical practice, and do not relieve the needfor a first device to administer the anaesthetic followed by a seconddevice to start the IV, both of which must be included in the IV kit andhandled separately.

Also of concern is safety for the health practitioner. A device forstarting an IV typically includes provision for a retractable hypodermicneedle, where the sharp end of the needle is urged inside a housingafter activation of a spring mechanism by the user. Surprisingly, whilesharps are clearly a factor in transmission of blood borne disease,retractable needles have not been associated with higher safety incannulation procedures, perhaps because of accidental cuts whileoperating the mechanism or spatter due to motion of spring-loaded parts.Spring-loaded retractable needles have also been associated withdecreased success in pediatric patient populations due to accidentalpremature retraction of the trocar. Retractable needles are described,for example, in U.S. Pat. Nos. 5,195,985, 5,201,719, 5,885,257,6,210,371, 6,210,375, and 6,368,303.

An alternative is an extensible sheath, which may be deployed to advanceover the trocar on activation of a spring mechanism by the user, such asis described in U.S. Pat. No. 6,685,676. This mechanism is less likelyto be associated with blood splatter but is complex to manufacture andoperate.

There is also a need in the art for a convenient single-dose syringe ordevice permitting point of care administration of a buffered anaestheticsubcutaneously prior to the cannulation. Because it is desirable toprepared the buffered anaesthetic solution immediately before or at thetime of use, as shown by Dhaliwal (FIG. 4, U.S. Pat. No. 5,261,903) animproved device or method will supply the anaesthetic and bufferseparately in an inexpensive container and is configured to mix the twoformulations at the time of injection. Globally the market forintravenous cannulas is estimated to be more than one billion dollarsannually. Thus, there is a need in the art for a device and method forstarting an IV that overcomes the above disadvantages and has otheradvantages to improve the process of starting an IV.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIGS. 1A through 1E depict steps of a method for starting an IV. In thefinal step, the soft cannula is released from the trocar and remains inthe vein (vein not shown).

SUMMARY

IV therapy is widely used in delivering medications, but pain is acommon and undesirable factor in starting an IV and can lead to patientavoidance, trauma, and complications. To reduce pain, prophylacticsubcutaneous injection of lidocaine HCl NF has been used. Unfortunately,the low pH of lidocaine HCl is associated with an initial burningsensation, thus diminishing its palliative value. To reduce the pain ofinjection of lidocaine, it is known to use smaller needles and bufferedsolutions. But these buffered solutions are very unstable, so thesolution must be made shortly before use. In sum, this chain of factorscombines to diminish the widespread use of what is an otherwiseeffective and helpful tool in reducing pain during IV cannulation.

An improved device for starting an IV would be multifunctional,serving 1) for preparation of buffered anaesthetic, 2) foradministration of the local anaesthetic, and 3) for inserting thecannula. The device is optionally operable with one hand during thecannulation procedure, requires no assembly for use, includes a safetymechanism for minimizing exposure to sharps.

Similar concerns arise with other local anaesthetics in the same class.The use of a low pH to stabilize lidocaine is also useful in stabilizingcombinations of lidocaine with epinephrine, which is used to extend theduration of anaesthesia in other procedures. Other combinations ofmedications with buffers or medications with other medications can leadto instability of the resultant solution, necessitating use immediatelyafter preparation.

To address these issues, we have devised a method for preparing amixture of lidocaine and sodium bicarbonate USP in a convenient syringeformat. The two solutions are prepared in a double-chambered reservoir.Shattering the reservoir, for example with a plunger of a syringe,releases the liquids and permits mixing so that, for example, a bufferedsolution of lidocaine can be injected via a needle attached to thesyringe.

A fine-gauge hypodermic needle for injection of the buffered mixture oflocal anesthetic is nested within the bore of a trocar having a largeinside diameter. The trocar supports a soft cannula that slides onto theoutside surface of the trocar. Thus the device serves multiple functionsand its method of use can be described as a series of steps, firstinjection of the buffered local anesthetic through the smaller needleunder the skin near the planned site for insertion of the intravenouscannula, followed by withdrawal of the smaller needle through thetrocar, then insertion of the trocar into a vein, followed by withdrawalof the trocar, leaving the soft cannula in the vein.

In a preferred embodiment, the invention is a method for preparing andinjecting a mixture of lidocaine and sodium bicarbonate buffer to form abuffered anaesthetic solution during administration and not sooner,preparing the patient by administering the local anaestheticsubcutaneously, and then implanting a soft cannula in a peripheral vein,where the mixing, injecting and implanting is performed with on-boardreservoirs for the liquids to be administered and comprising a smallneedle nested in a trocar, where the cannula is ensheathed on the trocarand the single device is used in consecutive steps to complete theentire procedure. The buffered mixture is preferably at about neutralpH.

Although the following detailed description contains many specificdetails for the purposes of illustration, one of skill in the art willappreciate that many variations and alterations to the following detailsare within the scope of the invention. Accordingly, the exemplaryembodiments of the invention described below are set forth without anyloss of generality to, and without imposing limitations upon, theclaimed invention.

DETAILED DESCRIPTION Definitions

Certain meanings are defined here as intended by the inventors, ie. theyare intrinsic meanings. Other words and phrases used here take theirmeaning as consistent with usage as would be apparent to one skilled inthe relevant arts. When cited works are incorporated by reference, anymeaning or definition of a word in the reference that conflicts with ornarrows the meaning as used here shall be considered idiosyncratic tosaid reference and shall not supersede the meaning of the word as usedin the disclosure herein.

“IV”: Intravenous therapy or IV therapy is the giving of liquidsubstances directly into a vein. It can be intermittent or continuous;continuous administration is called an intravenous drip. The wordintravenous simply means “within a vein”, but is most commonly used torefer to IV therapy.

Hypodermic needle: as used here, a hollow needle used for delivering aliquid medication subcutaneously. The hypodermic needle is typically asmaller needle used for subcutaneous administration of an anaesthetic.While commonly used with a hypodermic syringe, may also be used with thenovel syringes of the invention.

“Cannula” or “catheter”: as used here, a slender, hollow, flexible tubefor insertion into a vein; typically supported during the insertionprocedure by a trocar, which is withdraw after the cannula is seated inthe vein.

Trocar: a specialized needle used for supporting a cannula or catheterduring the cannulation procedure; a sharp-tipped shaft on which thecannula is supported as a close-fitted sleeve. The trocar is adapted forpiercing the epidermis and vascular wall. After cannulation, the trocaris withdrawn.

Syringe: typically referring to a piston-type syringe with plunger andbarrel for injecting a liquid, may also refer to the novel syringes ofthe invention. Optionally a syringe is fitted at the injection tip witha detachable and interchangeable hypodermic needle. The syringes of theinvention may include integral, non-detachable hypodermic needles.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to”.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, the appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this specification are not necessarily all referring to thesame embodiment. The appended claims are not to be interpreted asincluding means-plus-function limitations, unless such a limitation isexplicitly recited in a given claim using the phrase “means for.”Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments.Therefore, the scope of the present invention should be determined notwith reference to the above description but should, instead, bedetermined with reference to the appended claims, along with their fullscope of equivalents.

DRAWINGS

In a first embodiment, the invention utilizes a hypodermic needle toadminister an anaesthetic mixture and a trocar to implant an intravenoussoft cannula, where the needle, trocar and cannula are coaxially nested.In a second embodiment, an extensible safety sheath is also provided.While the explanation and description shown herein is generally directedat administration of a lidocaine/bicarbonate buffered mixture andsubsequent steps of starting an IV, the invention is not necessarilylimited thereto, and may also encompass a novel syringe dosing systemfor administering a therapeutic mixture where the mixture is made duringthe injection, or where the composition of the mixture is made duringthe injection with a fixed proportion.

By a first manufacturer, a duplex ampoule is realized by encapsulationof a first liquid in a first reservoir and a second liquid in a secondreservoir where the two reservoirs are frangible and are separated by anintermediate frangible film therebetween. The reservoirs are cup shapedand are optionally formed by vacuum molding. Once filled, the firstreservoir is covered by the intermediate layer and sealed and thesubassembly containing the first fluid is then inverted and placed overthe second reservoir after filling the second fluid. The entire assemblyis then sealed around the edges and any flash removed. While glass maybe used for making duplex ampoules of this kind, a preferred material isa highly brittle shatter-prone plastic such as a polystyrene, polymethylmethacrylate, acrylonitrile-styrene and the like, such materialstypically having high crystallinity and low ductility. These materialsare prone to fracture under strain and fragment rather than fold. Theirtoughness can be adjusted by blending for example with polypropylene,polyethylene terephthalate, polylactams, and so forth, as is known inthe art. By scoring or etching lines in the material, yield points canbe prestressed.

Ultrasonic welding is sufficient to form suitable seals. Materials arechosen for compatibility with the liquid to be contained therein. By asecond manufacturer, a blow-fill-seal process to form a duplex ampouleis accomplished in a single step.

To assemble the device, the plunger, duplex ampoule, and filter pad maybe viewed as a first cluster, the hypodermic needle, mounted in aslidable sealing disk, latch release and short coil spring are a secondcluster, and the trocar with second slidable sealing disk and associatedlong coil spring, form a third cluster, where the three clusters areinserted into the syringe barrel starting with the third cluster so thatthe hypodermic needle inserts through the inside diameter of the trocarand the needle end protrudes from the tip of the device. The secondtriggering latch is used to affix the trocar in place, holding the longspring in compression. The cannula is then slipped over the trocar andsecured on the nose of the syringe barrel.

As shown in FIG. 1, starting an IV is executed by a series of steps. InFIG. 1A, the preloaded device 100, such as would be provided with a kitfor starting an IV, is ready for use. The device comprises asyringe-like body with syringe barrel 101 and piston 102 and a duplexampoule 103 disposed in the syringe barrel.

In FIG. 1B, the duplex ampoule 103 is shattered, releasing theanaesthetic and the buffered solution, thereby forming an injectablemixture 104. This may be accomplished by pressure on the syringe pistonin its barrel. Continued pressure on the syringe piston, as shown inFIG. 1C, forces the buffered mixture through a filter 105, into thehypodermic needle 106 and out the needle tip 107. It is in this stepthat a subcutaneous wheal of local anaesthetic is injected at the sitewhere the IV will be placed, as indicated for illustration by droplet offluid 109. Then, using the first release latch (110, first black arrow,FIG. 1D), the hypodermic syringe is withdrawn into the trocar 111. Ashorter spring member 112, which was under compression, urges the needleback inside the barrel of the syringe when the latch is released,withdrawing the needle tip inside the trocar. The exposed lancing tip113 of the trocar is then used to insert the ensheathed cannula 115 intothe vein (not shown) and the trocar is withdrawn. By pressing the secondrelease latch (116, second black arrow, FIG. 1E), the trocar isretracted within the body of the syringe barrel. A longer spring member117, which was under compression, urges the trocar to retract into thebarrel housing of the syringe body. The cannula 115 remains in the vein.

Advantageously, the method minimizes pain to the subject in need of IVtherapy. Yet more advantageously, in the hands of a skilled user themethod for starting an IV may be accomplished with one hand while theother hand performs manipulations on the vein and IV site.

Additional steps for attaching an IV fluid to the cannula areaccomplished as is generally known to one skilled in the art.

A device for the method and instructions for its use are provided by amanufacturer. Thus the method can be characterized as having the stepsof:

providing a device havingi) a first reservoir of a local anaesthetic and a second reservoir of abuffer, wherein the reservoir is disposed within a body of a syringe,the syringe with piston and barrel;ii) a hypodermic needle having a first outside diameter, a fluidreceiving end and a needle tip;iii) a trocar having an inside diameter incrementally greater than thefirst outside diameter of the hypodermic needle, the trocar having alancing tip;iv) a cannula having an inside diameter configured for slidably fittingover the trocar and detachably attaching to an adaptor on the barrel;wherein the hypodermic needle is coaxially nested inside the trocar withthe needle tip projecting anteriorly therefrom and slidingly retractabletherethrough, and the trocar is coaxially nested inside the cannula withthe lancing tip projecting anteriorly therefrom and slidinglyretractable therethrough; and,providing instructions toa) first mix the local anaesthetic and the buffer, thereby forming abuffered anaesthetic mixture;b) then insert the needle tip under the skin of a subject in need of anIV and, using the plunger, inject via the fluid receiving end a wheal ofthe buffered anaesthetic mixture thereunder;c) then slidingly retract the needle tip of the hypodermic needle intothe trocar, thereby enclosing the needle tip;d) then insert the lancing tip of the trocar into a vein at an IV siteselected on the subject in proximity to the wheal, the wheal foranesthetizing the IV site;e) detaching the cannula from the syringe and withdrawing the trocarfrom the vein, while leaving the cannula in place; andf) slidingly retracting the trocar into the body of the syringe, therebyenclosing the lancing tip. The method generally also includes steps forsecure the cannula to the IV site and for attaching an IV fluidreservoir to the cannula. The instructions generally also include a stepfor disposing of the syringe body with internally retracted sharps, i.e.both the needle tip of the hypodermic needle and the lancing tip of thetrocar are safely retracted inside the barrel of the syringe so as tominimize risk to personnel handling the used device.

All publications and patent documents cited in the specification and inany accompanying information disclosure statement are herebyincorporated by reference in their entirety as may be useful to theunderstanding of the invention. Although the foregoing invention hasbeen described in some detail by way of illustration, explanation andexample, it will be obvious to one skilled in the art that certainchanges or modifications may be practiced within the scope of theclaims. Therefore, the invention is not to be limited to any oneparticular embodiment or combination of embodiments disclosed here, butthe scope of the appended claims is to be construed as broadly aspermitted by law.

I claim:
 1. A method for starting an IV in a peripheral vein, whichcomprises providing a device having i) a first reservoir of a localanaesthetic and a second reservoir of a buffer, wherein said reservoiris disposed within a body of a syringe, said syringe with piston andbarrel; ii) a hypodermic needle having a first outside diameter, a fluidreceiving end and a needle tip; iii) a trocar having an inside diameterincrementally greater than said first outside diameter of saidhypodermic needle, said trocar having a lancing tip; iv) a cannulahaving an inside diameter configured for slidably fitting over saidtrocar and detachably attaching to an adaptor on said barrel; whereinsaid hypodermic needle is coaxially nested inside said trocar with saidneedle tip projecting anteriorly therefrom and slidingly retractabletherethrough, and said trocar is coaxially nested inside said cannulawith said lancing tip projecting anteriorly therefrom and slidinglyretractable therethrough; and, providing instructions to a) first mixsaid local anaesthetic and said buffer, thereby forming a bufferedanaesthetic mixture; b) then insert said needle tip under the skin of asubject in need of an IV and, using said plunger, inject via said fluidreceiving end a wheal of said buffered anaesthetic mixture thereunder;c) then slidingly retract said needle tip of said hypodermic needle intosaid trocar, thereby enclosing said needle tip; d) then insert saidlancing tip of said trocar into a vein at an IV site selected on saidsubject in proximity to said wheal, said wheal for anesthetizing said IVsite; e) detaching said cannula from said syringe and withdrawing saidtrocar from said vein, while leaving said cannula in place; and f)slidingly retracting said trocar into said body of said syringe, therebyenclosing said lancing tip.
 2. The method of claim 1, which furthercomprises an instruction for safely disposing of said syringe body withretracted sharps.
 3. The method of claim 1, which further comprises aninstruction to secure the cannula to the IV site and attach an IV fluidto said cannula and administering said IV fluid via said vein.
 4. Themethod of claim 1, where said step for triggeredly retracting saidhypodermic needle comprises actuating a nested spring-loaded mechanismwith trigger for actuating same.
 5. The method of claim 1, where saidstep for triggeredly retracting said trocar comprises actuating a nestedspring-loaded mechanism with trigger for actuating same.
 6. The methodof claim 1, wherein said first reservoir and said second reservoir areformed by a process of blow fill molding in a frangible duplex ampoule.7. The method of claim 1, wherein said steps a)-f) are optionallyaccomplished with one hand while the other hand performs manipulationson the vein and IV site.
 8. A device for starting an IV in a peripheralvein, which comprises a) a first reservoir of a local anaesthetic and asecond reservoir of a buffer, wherein said reservoir is disposed withina body of a syringe, said syringe with piston and barrel; b) ahypodermic needle having a first outside diameter, a fluid receiving endand a needle tip; c) a trocar having an inside diameter incrementallygreater than said first outside diameter of said hypodermic needle, saidtrocar having a lancing tip; d) a cannula having an inside diameterconfigured for slidably fitting over said trocar and detachablyattaching to an adaptor on said barrel; and wherein said hypodermicneedle is coaxially nested inside said trocar with said needle tipprojecting anteriorly therefrom and slidingly retractable therethrough,and said trocar is coaxially nested inside said cannula with saidlancing tip projecting anteriorly therefrom and slidingly retractabletherethrough.